Innovative Architecture for Dual-band WLAN and MIMO Front- end Module Based on a Single Pole, Three Throw Switch-plexer Chun-Wen Paul Huang, William Vaillancourt, Philip Antognetti, Tony Quaglietta, Mike McPartlin, Mark Doherty, and Christophe Masse SiGe Semiconductor, Andover, MA 01810, USA Abstract — An innovative architecture for a dual-band front-end module (FEM) for WiFi and MIMO radios is presented. The FEM consists of a dual-band power amplifier and a SP3T switch-plexer. The SP3T switch-plexer has a SP3T switch and an integrated Rx diplexer. Tx switch paths show 0.1 dB compression at > 33.5 dBm with <1 dB insertion loss (IL) along with > 18 dB isolation. Rx switch/diplexer path has < 2.0 dB IL for both bands. The band selectivity is > 15 dB. These qualities simplify the construction of dual-band FEM by reducing assembly complexity and post PA loss resulting in a high band performance of 3% EVM at 18 dBm output and < -50 dBm/MHz harmonic emissions in a 4 x 4 mm package. Index Terms — Dual-Band WLAN/MIMO front-end IC’s, switch designs, WLAN PA, diplexer designs. I. INTRODUCTION Wireless Local Area Network (WLAN) remains one of fastest growing areas of data communications in this decade. Originally designed for computer networking, WLAN has been widely implemented in many other consumer electronic devices, such as cellular phones, security monitoring, personal data assistants, gaming systems, and multiple media (video, data, and voice) distribution [1]. Moreover, the demand for higher throughput rates have resulted in the implementation of multiple-input, multiple-output (MIMO) techniques to increase the data rate from the original 54Mbps to a minimum of 108 Mbps. Currently, most WiFi and MIMO radios operate at 2.4 GHz having 3 channels for 54Mbps operation. For MIMO applications, channel bonding techniques are used so more bandwidth is needed. From a market perspective, dual-band WLAN and MIMO radios are quickly being deployed to resolve the 2.4 GHz bandwidth congestion. For computer mini-cards and portable electronics, a front-end module (FEM) is the preferred design implementation. When MIMO is used in portable electronics or other miniature network cards, FEM’s simplify the design and layout of the small form- factor, low cost PC card based WLAN radio solutions. In this paper, a novel dual-band FEM architecture is presented (as shown in Fig. 1) which consists of only two components, -- a single pole three throw (SP3T) switch- plexer and a dual-band PA. The SP3T switch-plexer is realized in GaAs pHEMT technology and consists of a dual-band SP3T switch and a diplexer integrated in the Rx switch path. As shown in Fig. 2, the diplexer only requires 140 x 1100um 2 out of 680 x 1600um 2 overall die size. In Fig. 1, switch-plexer is the last component in the FEM, so it is optimized for maximized linearity, linear power handling, low loss and compatible for use with positive CMOS control signals. In addition, the switch has a turn on speed of less than 50 nS which does not delay the PA settle time and simplifies the post PA circuitry by removing the Tx diplexer shown in Fig. 3. OMN Dual Band SP3T Switch-plexer Txg Txa Rxg Rxa Ant Dual-band PA OMN Bias CKT/ Controller Fig. 1. Novel architecture for a dual-band WLAN FEM in an a/b/g/n radio. Fig. 2. Die photo for the SP3T switch-plexer. In contrast to a conventional FEM architecture [2] as shown in Fig. 3, the proposed architecture shown in Fig. 1 has a very low assembly complexity and reduces the post PA loss by eliminating use of a diplexer in the Tx path. Rx Diplexer SP3T T/R Switch 978-1-4244-3376-6/978-1-4244-3378-0/09/$25.00  2009 IEEE 2009 IEEE Radio Frequency Integrated Circuits Symposium RMO4A-3 281